532 Lord Rayleigh on the 



Distillation of Hydrochloric Acid. — Sept. 13, 1898. 



No. 



Volume 

 in c.c. 



Specific 

 gravity. 



Total 

 weight. 



Per- 

 centage 

 of HCl. 



Weight 



of 



HCl. 



Weight 



of 



H 2 0. 



HCl re- 

 maining 

 in re- 

 tort. 



H 2 re- 

 maining 

 in re- 

 tort. 



Total 

 remain- 

 ing. 



Per- 

 centage 

 of HCl 

 remain- 

 ing. 







1800 



1-031 



18558 



6-0 



111-4 



1744-4 









6-0 



1 



250 



1-0013 



25032 



0-26 



0-65 



249-7 



110-7 



1494-7 



1605-4 



6-9 



2 



250 



1-0023 



250-58 



0-45 



1-12 



249-4 



109-6 



1245-3 



1354-9 



8-1 



3 



250 



1-0038 



25095 



0-76 



1-90 



249-0 



107-7 



996-3 



1103-9 



9-8 



4 



250 



1-0076 



25190 



1-53 



3-86 



248-0 



1040 



748-3 



852-3 



12-2 



The first column contains the numbers of the successive 

 distillates from 1 to 4, the entry referring to the mixture 

 with which the retort was originally charged. The volume 

 of this mixture was 1800 c.c. of specific gravity 1*031 and 

 of 6*0 per cent, strength. Of the total weight 1855*8 gms., 

 111*4 gms. is hydrochloric acid and 1744*4 gms. water. In 

 like manner the volume of the first distillate is 250 c.c, the 

 specific gravity 1*0013, the total weight 250*32 gms., of 

 which 0"65 gms. is HCl and 249*7 gms. H 2 0. The residue 

 in the retort after the first 250 c.c. has been distilled over is 

 accordingly composed of 111*4 — 0*65 or 110*7 gms. HCl and 

 1744*4-249*7 or 1494*7 gms. H 2 0, making 1605-4 gms. in 

 all. At this stage the percentage strength of the liquid re- 

 maining in the retort is 6*9. The strengths of the liquid in 

 the retort after the 1st, 2nd, . . . 4th distillates have been 

 removed are found in this way to be 6"9 ; 8*1, 9*8, and 12*2 

 per cent. The first distillate, whose strength is 0*26 per cent., 

 thus corrresponds with a liquid whose strength varied from 

 6*0 to 6*9 per cent , on an average 6*45 per cent. We thus 

 obtain the following corresponding strengths : — 



Percentage Strengths. 



Liquid. 



Vapour. 



6*45 



0*26 



7*50 



0*45 



8*95 



0*76 



11*00 



1*53 



It is hardly worth while to record all the separate results 

 In addition to the above the following will suffice for the 

 construction of the curve 



In the three last the strengths of 



